I think they decided they couldn't make the 5 any cheaper in the short term, so they changed their product cycle.
It is a deliberate move and the key is now to understand why they did it.
Of course the issue in this argument is the App store. You could argue that by building a huge user base could allow you to shift your profits from hardware to software in the long run.
I'd also look to Intel and Microsoft if I was wondering where the profit in the PC market went. I'm guessing your figures for PC profit don't include the little known Wintel duo?